Apparatus for compensation of the operation of a fuel injection device for an internal combustion engine

ABSTRACT

A fuel injection device for an internal combustion engine is subjected to the action of two spring units mounted in a suction chamber connected to the suction inlet leading to the engine such that the first spring unit becomes inoperative when the engine is under high load while the resilient action of the second spring unit varies with atmospheric pressure change. The suction chamber has front and rear diaphragm walls against which the second spring unit permanently bears, whereas the first spring unit is fixedly supported at its back end while its front end bears against the front wall when the suction pressure is high during low engine load and loses contact therewith when the suction pressure is low during high engine load. At the back of the suction chamber is a further chamber acting on the rear diaphragm wall and selectively connected by a changeover valve to the atmosphere or to the suction inlet depending on atmospheric pressure.

Unite States Patent 1 Ohama et al.

[54] APPARATUS FOR COMPENSATION OF THE OPERATION OF A FUEL INJECTION DEVICE FOR AN INTERNAL COMBUSTION ENGINE [75] Inventors: Yasumichi Ohama, Tokyo; Hiroshi Kogure, Saitama, both of Japan [73] Assignee: Honda Giken Kogyo Kabushiki Kaisha, Tokyo, Japan [22] Filed: Nov. 3, 1971 21 Appl.No.: 195,181

[30] Foreign Application Priority Date [56] Reiereuces Cited UNITED STATES PATENTS 2,233,035 2/1941 Schweizer et al. ..l23/l40 MP 1 Mar. 27, 1973 Dahl et al... ..l23/140 MC Kranc ..l23/l40 MP [57] ABSTRACT A fuel injection device for an internal combustion engine is subjected to the action of two spring units mounted in a suction chamber connected to the suction inlet leading to the engine such that the first spring unit becomes inoperative when the engine is under high load while the resilient action of the second spring unit varies with atmospheric pressure change. The suction chamber has front and rear diaphragm walls against which the second spring unit permanently bears, whereas the first spring unit is fixedly supported at its back end while its front end bears against the front wall when the suction pressure is high during low engine load and loses contact therewith when the suction pressure is low during high engine load. At the back of the suction chamber is a further chamber acting on the rear diaphragm wall and selectively connected by a changeover valve to the atmosphere or to the suction inlet depending on atmospheric pressure.

6 Claims, 2 Drawing Figures PATENTEUHARZYIHYS $722,487

SHEET 10F 2 'NV'TINTORS PATENTEUHARZYIHH 87 SHEET 2 BF 2 INVENTOR 0% @Ma BY h (hm/L kw;

APPARATUS FOR COMPENSATION OF THE OPERATION OF A FUEL INJECTION DEVICE FOR AN INTERNAL COMBUSTION ENGINE BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates to the control of a fuel injection device for an internal combustion engine and more particularly to the control of a fuel injection device which is operated by the negative pressure in a suction inlet to the engine.

The fuel injection apparatus 6 comprises a plunger type injection pump 9 connected to a fuel tank 7 through a pump 8. A plunger 10 of the injection pump 9 is forced to reciprocate by a rotating cam 12 which is mounted on a rotating shaft 11 driven by the engine 1 so as to be rotatable therewith but slidable relatively thereto. The cam 12 is so formed that the cam height thereof is gradually increased from its front end to its rear end, so that by a slidable movement of the cam 12,

the stroke of plunger 10 is changed and accordingly the pump 9 is changed in its injection amount.

The invention specifically relates to apparatus for controlling such fuel injection device to compensate for changes in atmospheric pressure.

2. Description of the Prior Art It has been hitherto proposed that, in such a fuel injection device operated by negative pressure and in which the injection amount of fuel is automatically controlled in accordance with the negative pressure in the suction inlet to the internal combustion engine, the control operation of the fuel injection device is compensated with change of atmospheric pressure, for example, at the time when the atmospheric pressure is lowered beyond a predetermined level.

It is, however, not preferable to effect this kind of atmospheric pressure compensation when the engine is in a low load operation. Namely, when the engine is in low load operation, the suction pressure is so large that the fuel injection device provides decreased fuel injection amount whose metering is comparatively delicate. Therefore, when the atmospheric pressure compensation is effected under this condition, there is caused a comparatively large change in fuel injection amount and the engine operation is liable to become unstable.

SUMMARY OF THE INVENTION An object of this invention is to provide an apparatus wherein the atmospheric pressure compensation is effected when the engine is in high load operation but substantially not effected when the engine is in low load operation.

According to the invention, there are provided two spring units one for low load and the other for high load for controlling the injection amount of fuel in accordance with the negative pressure in the suction inlet to the internal combustion engine, the arrangement being such that during high engine load, the spring unit for low load becomes inoperative and the spring unit for high load undergoes changes in its resilient force in response to change of atmospheric pressure.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a diagrammatic sectional side view of the apparatus according to the invention; and

FIG. 2 is a sectional side view of a portion of the apparatus in another condition of operation.

DETAILED DESCRIPTION Referring to thedrawing, numeral 1 denotes an internal combustion engine, and numeral 2 denotes a suc- The slide movement of the cam 12 is effected by the negative pressure of the engine 1. Namely, a diaphragm 14 carries a push rod 13 projecting forwardly therefrom for pushing the cam 12 from behind, and at the rear side of the diaphragm 14 there is formed a negative pressure chamber 15 connected to the suction pressure opening 4. The diaphragm 14 is urged forward by a spring 16 for high load and two springs 17 for low load. Thus, if the negative pressure in passage 2 is decreased, the diaphragm 14 is advanced by the pushing action of the springs l6, l7 and accordingly the cam 12 is advanced by push rod 13 so that the plunger 10 is increased in stroke and the injection amount is increased. If, however, the negative pressure is increased, the diaphragm 14 is retracted against the action of the springs 16, 17 and the cam 12 is retracted, so that the stroke of plunger 10 is decreased and the injection amount is decreased. Numeral I8 denotes a spring urging the cam 12 rearward.

The rear wall of the negative pressure chamber 15 is formed as a diaphragm 20 urged forward by a spring 19, and at the rear side of diaphragm 20 there is formed a second negative pressure chamber 21.

The interior of chamber 21 is selectively connected through a changeover valve 22 to the ambient atmosphere or the suction pressure opening 4. The valve 22 is so arranged that in ordinary condition it is located at one side position to connect the interior of the chamber 21 to the atmosphere but it is moved to the other side position upon actuation of a detecting device 23 by a change in atmospheric pressure, for example,

by a lowering thereof to a predetermined level. Namely, by the operation of the detecting device 23, a contact 24 is closed and a solenoid 25 is energized and thereby the valve 22 is moved to its changeover operation.

The spring 16 for high load is interposed between the diaphragms 14, 20 so that it will always be in an operative condition, but each spring 17 for low load is held at its base end by a respective stationary receiving seat 26 and each spring 17 has a comparatively short free length, so that if the diaphragm 14 is advanced beyond a predetermined distance, each spring 17 is left in a position separated from the diaphragm 14 as illustrated in FIG. 2.

Thus, when the engine 1 is in its high load operation, the negative pressure is comparatively small and the diaphragm 14 is advanced such that only the spring 16 is operative as illustrated in FIG. 2. When in this condition the detecting device 23 is operated by a change of atmospheric pressure and the suction pressure is introduced into the chamber 21, the diaphragm 20 is retracted and the action of spring 16 is decreased, whereby there is caused a change in the operation characteristic feature of the diaphragm l4, and correspondingly in the characteristic feature of the control operation of the injection amount. Thus, atmospheric pressure compensation is effected. When the engine is in its low load operation, the negative pressure is comparatively large so that the diaphragm 14 is retracted and the springs 17 together with the spring 16 are brought into operative condition, so that even when from this condition the diaphragm 20 is retracted and the action of the spring 16 is decreased, only spring 16 is affected and the two springs 17 remain in operative condition and therefore the entire resilient force is not largely changed. Thus, there is no large change in the operation characteristics of the diaphragm 14, that is, in the control operation of the amount of fuel injection and consequently there is very little atmospheric pressure compensation.

Thus, according to this invention, atmospheric pressure compensation is effected only when the engine is in a high load operation, and the inconvenience caused by atmospheric pressure compensation at the time of low load operation is eliminated. This is achieved by the apparatus of the invention which broadly contemplates means responsive to the negative pressure in the inlet and acting on the fuel injection device to regulate the amount of fuel injection to the engine, and means responsive to atmospheric pressure and coupled to the first said means to control the action thereof on the fuel injection device, the first said means comprising first and second spring assemblies applying resilient action to the fuel injection device and subjected to negative pressure in the engine such that the first spring assembly is rendered inoperative when the engine is under high load, said second spring assembly being acted on by the second said means to undergo variation in its resilient action on the fuel injection device upon variation in atmospheric pressure whereby under high load only the second spring assembly acts on the fuel injection device and variation in atmospheric pressure has pronounced effect on the fuel injection device whereas under low load both spring assemblies act on the fuel injection device and the effect of the variation in atmospheric pressure is minimized.

What is claimed is:

1. Apparatus for the compensation of the ope-ration of a fuel injection device for an internal combustion engine, the fuel injection device being operated by the negative pressure in a suction inlet to the engine, said apparatus comprising means responsive to the negative pressure in the inlet and acting on the fuel injection device to regulate the amount of fuel in injection to the engine, and means responsive to atmospheric pressure and coupled to the first said means to control the action thereof on the fuel injection device, the first said means comprising first and second spring assemblies applying resilient action to the fuel injection device and subjected to negative pressure in the engine such that the first spring assembly is rendered inoperative when the engine is under high load, said second spring assembly being acted on by the second said means to undergo variation in its resilient action on the fuel injection device upon variation in atmospheric pressure whereby under high load only the second spring assembly acts on the fuel injection device and variation in atmospheric pressure has pronounced effect on the fuel injection device whereas under low load both spring assemblies act on the fuel injection device and the effect of the variation in atmospheric pressure is minimized.

2. Apparatus as claimed in claim 1 wherein the first said means comprises a suction chamber connected to the suction inlet to the engine, said suction chamber including a front diaphragm wall coupled to the fuel injection device, said first and second spring assemblies being in said suction chamber, said first spring assembly engaging said diaphragm wall when the suction pressure in the inlet is high during low engine load and being disengaged from said wall when the suction pressure in the inlet is low during high engine load, said second spring assembly being in permanent engagement with said wall.

3. Apparatus as claimed in claim 2 wherein said first spring assembly comprises two spring members.

4. Apparatus as claimed in claim 2 wherein said suction chamber includes a rear diaphragm wall against which the second spring assembly is engaged.

5. Apparatus as claimed in claim 4 wherein said means responsive to atmospheric pressure to control the action of the first means on the fuel injection device comprises a second suction chamber behind said rear diaphragm wall, and means responsive to atmospheric pressure for selectively supplying atmospheric pressure or the suction pressure at the engine inlet to said second suction chamber.

6. Apparatus as claimed in claim 3 wherein said spring members have fixed back ends and free front ends which bear against said front diaphragm wall when the suction pressure in the inlet is high and lose contact therewith when the suction pressure is low. 

1. Apparatus for the compensation of the operation of a fuel injection device for an internal combustion engine, the fuel injection device being operated by the negative pressure in a suction inlet to the engine, said apparatus comprising means responsive to the negative pressure in the inlet and acting on the fuel injection device to regulate the amount of fuel in injection to the engine, and means responsive to atmospheric pressure and coupled to the first said means to control the action thereof on the fuel injection device, the first said means comprising first and second spring assemblies applying resilient action to the fuel injection device and subjected to negative pressure in the engine such that the first spring assembly is rendered inoperative when the engine is under high load, said second spring assembly being acted on by the second said means to undergo variation in its resilient action on the fuel injection device upon variation in atmospheric pressure whereby under high load only the second spring assembly acts on the fuel injection device and variation in atmospheric pressure has pronounced effect on the fuel injection device whereas under low load both spring assemblies act on the fuel injection device and the effect of the variation in atmospheric pressure is minimized.
 2. Apparatus as claimed in claim 1 wherein the first said means comprises a suction chamber connected to the suction inlet to the engine, said suction chamber including a front diaphragm wall coupled to the fuel injection device, said first and second spring assemblies being in said suction chamber, said first spring assembly engaging said diaphragm wall when the suction pressure in the inlet is high during low engine load and being disengaged from said wall when the suction pressure in the inlet is low during high engine load, said second spring assembly being in permanent engagement with said wall.
 3. Apparatus as claimed in claim 2 wherein said first spring assembly comprises two spring members.
 4. Apparatus as claimed in claim 2 wherein said suction chamber includes a rear diaphragm wall against which the second spring assembly is engaged.
 5. Apparatus as claimed in claim 4 wherein said means responsive to atmospheric pressure to control the action of the first means on the fuel injection device comprises a second suction chamber behind said rear diaphragm wall, and means responsive to atmospheric pressure for selectively supplying atmospheric pressure or the suction pressure at the engine inlet to said second suction chamber.
 6. Apparatus as claimed in claim 3 wherein said spring members have fixed back ends and free front ends which bear against said front diaphragm wall when the suction pressure in the inlet is high and lose contact therewith when the suction pressure is low. 